Another Poverty Grass

Might as wellcontinue with another depressing range story because at the time of this writing it looks like the hot dry spring will continue into a hotter and drier summer. I hope I’m wrong.

Recovery of our grazing lands at this time depends 99 % on rainfall and 1% on management, but it’s always good to think about the plants that we need to know more about in our attempt to make ranching a sustainable enterprise.

Red threeawn is another poverty grass. Its leaves are short and thin without much to graze on. It matures in a hurry and quickly looses any forage value for livestock. Once it was more common on the ranch than it is now. I remember seeing a sea of red on our Mesquite flats in early summer when the grass was full of seed heads. The red comes from the long awns or tails of the seeds which are important in pushing the seed into the soil to establish a new plant (and, unfortunately, into the wool and hair of sheep and goats). Why they are red defies explanation, for sure it’s not to attract pollinators. All grasses are wind pollinated, and there is no need for color, attractive odor, or nectar to attract Butterflies and Bees.

Red threeawn takes advantage of soil disturbance to get established. Heavy grazing and drought that destroy the turf allow the seeds to penetrate the soil and benefit from the light showers that wet the top of the ground. Individual plants last a few years, and with time, they are replaced with better adapted plants, depending on available seed, adequate moisture and protection from heavy grazing. I’m confident the abundant plants I remember were established in the 1930’s and again in the 50’s and were less obvious as Dad became a better manager.

Red threeawn, sometimes called Purple threeawn, has the scientific name of Aristida purpurea var. longiseta. It extends from Canada to northern Mexico as a rather variable plant. In recent years it has been grouped with one big taxonomic mess of perennial threeawns consisting of about seven species, now varieties, in Aristida pupurea.

Today on the ranch it exists as a minor species. Red threeawn establishes easily on two rather different soil conditions. On a repeatedly overgrazed Mesquite flat it can be a dominant grass, a red carpet when the seedheads are ripe. And it can be the only grass growing on Harvester ant beds. It is easy to spot an ant bed in the pasture every 100 feet or so by the Red threeawn, which because of the weather has been bleached to straw color, no longer red.

The part of the ranch that I inherited was extremely overgrazed in 1938 when Dad acquired it. Under his management he has left it better than he found it, and I am intent on doing the same. And that means less Red threeawn and the other poverty grasses: Texas grama, Red grama, and Hairy tridens.

Reading The Landscape

A Edwards Plateau pasture in dry winter. What kind of tree is prominent in the center? What is the dark gray green understory shrub? What is the green plant in the fenceline? —JL

Jake’s comments: The tree is Chittamwood or Gum Bumelia which reacts to Mistletoe by making “witches broom” clusters; beneath is Algerita; green plant in fenceline is Sacahuista or Beargrass, poisonous to sheep and goats in spring. It appears to be a well managed pasture with a bit too much Algerita. —JL